INVOLVEMENT OF A STEM-LOOP STRUCTURE IN THE LOCATION OF JUNCTION SITES IN VIRAL-RNA RECOMBINATION

Recombination between RNAs associated with turnip crinkle virus is tho ught to occur during plus-strand synthesis at motifs resembling the 5' -ends of genomic, subgenomic and satellite RNAs. Common structural reg ions encompassing the motifs have been found for major crossover sites on two different minus-strand templates, with junctions preferentiall y located in a single-stranded region at the 3' base of a hairpin. Bas e changes, deletions and compensatory alteration constructed in and ar ound the hairpin in the region of the turnip crinkle virus genomic RNA involved in recombination support the importance of the hairpin for n ormal crossover site selection. This region of the genomic RNA is also important for replication of the viral genomic RNA in plants and prot oplasts, suggesting a common link between sequences required for recom bination and viral replication.